Prostitutes in Ipswich are being given money by police and drug workers to stop them risking their lives by touting for business on the streets, it emerged yesterday.

As officers continue to hunt for a serial killer feared to have murdered five women, it was revealed that women who work in the red light area of the Suffolk town are receiving cash handouts.

Detective Chief Superintendent Stewart Gull urged prostitutes to stay off the streets, saying: "It's not safe to engage a client or punter at this time."

He would not say how much money the 30 to 40 women who work in Ipswich were being given, but added that because of the "financial support" there was "no reason to go with clients".

The money has been handed over by an unnamed charity to the multi-agency group, including police, which oversees community safety in Suffolk. Drug workers are also making sure prostitutes are receiving all the money they need. Julia Stephens, of Suffolk County Council, said the money was being used by the women to pay bills or meet loans repayments.

Police are considering the possibility that the women may have been incapacitated before they were murdered, possibly by being drugged. One line of inquiry will be to focus on the drug dealers they regularly used. Officers confirmed that toxicology tests were being conducted.

Mr Gull warned there was a chance that the killer could be forced into other areas by the massive manhunt taking place. He said neighbouring forces were taking extra precautions to make sure prostitutes working in cities such as Norwich and Cambridge were protected.

Questioned about the progress of the inquiry, detectives said they had made no arrests, executed no search warrants and seized no vehicles. They dismissed the suggestion that the killer or killers may have been taunting the police by continuing to target women in the midst of a huge manhunt.

But Mr Gull, who is overseeing the operation, said it was possible that the killer, who removed the women's clothes before dumping their bodies, might be keeping their clothes as a trophy.

Police denied some media claims that the victims' body hair had been shaved, a detail which had appeared to link the killings with an unsolved murder in East Anglia more than a decade ago.

Police have now established a cause of death for one of the two women, Paula Clennell, 24, whose bodies were found near Levington, east of Ipswich town centre, on Tuesday. She died as a result of "compression to the neck". Detectives also revealed they had learned that Ms Clennell was seen working on the streets in Ipswich in the early hours of Sunday morning - confirmation that the killer was confident enough to strike again even with dozens of officers already working on the deaths of three women whose bodies had been found by that time. Ms Clennell was seen at 12.20am in Handford Road, near where she lived.

The second body found near Levington, thought to be that of Annette Nicholls, 29, was removed from the scene yesterday and was being examined by a pathologist. Earlier this week it emerged that Anneli Alderton, 24, whose body was found on Sunday, had been asphyxiated. Toxicology tests are being carried out on the bodies of Gemma Adams, 25, and Tania Nicol, 19.

The investigators continued to receive a deluge of calls - 5,500 as of yesterday morning - and more than 1,000 emails. Many messages concerned the women's clothes and other personal belongings.

Officers are combing hours of CCTV footage and records of vehicles captured on number plate recognition systems. They are also examining phone records to try to find out who the women spoke to in the weeks before their deaths and to attempt to pinpoint their movements.

Police would like to speak to a woman who claimed she had seen Ms Alderton speaking to a "chubby-faced man with spectacles" driving a blue BMW, although the driver of the vehicle has been interviewed by police.